There was substantial upside if one bought Boeing stock” during prior strikes in 1989, 1995 and 2005, an analyst says, though a 2008 strike that coincided with the Great Recession was an outlier.

The strike is costing Boeing an estimated $1 billion a month, and new CEO Kelly Ortberg is working to keep the company afloat. Boeing is raising up to $25 billion through stock and debt offerings. It's arranging a $10 billion credit agreement with major lenders amid a production and regulatory crisis.

Boeing and its new management team have not matched the union demands, causing a pause in production at its factories and a huge cash burn that is draining the company's finances. Here's why this strike is a bad sign for Boeing's business and puts more strain on an already stretched balance sheet.